The neonatal mortality, growth, development and behavior of offspring of male rats, treated prior to mating with a narcotic, and drug naive females will be studied to determine whether these drugs given solely to the male damage their progeny. Cytogenetic and autopsy studies of the offspring of narcotized males will be employed to define the mechanism of neonatal death. The testes and semen of narcotized rats will also be examined to explain differences in conception rate. A comparative study of the effects of morphine and methadone will be accomplished. If deleterious effects are seen in the offspring of males pretreated with methadone similar studies of new narcotic and narcotic antagonists proposed for clinical use will be undertaken to establish their safety prior to extensive use in man.